RESUMO
Intracellular dialysis and fixed membrane potential techniques were used to study the extracellular influence of antiarrhythmic drugs--brazidole (a new derivative of 2-mercaptobenzimidazole), amiodarone, sotalol, and hydroxyzine (a tranquilizer) in concentrations 1, 10, 100 and 1000 microM--on the slow potassium ionic transmembrane current in isolated neurons of Lymnnaea stagnalis mollusks. All drugs produced a doze-dependent and reversible suppression of the potassium ion current and accelerated the inactivation kinetics. With respect to the degree of current suppression at 100 microM concentration, the preparations under study can be arranged in the following order: brazidole = hydroxyzine > amiodarone > sotalol. The drugs influence the membrane stability by changing nonspecific leak currents. The antiarrhythmic action of bradizole can be related to its high membranotropic activity.
